General PCB Manufacturing Pros and Cons

[Probb]

Hey guys,

I've recently partnered up with a buddy that has solid connections to a handful of Chinese fab houses that all make quality boards at a great price.
We're looking to start-up a little website that makes ordering PCB boards quick and painless. Our prices would be right in the ball park of what PCBWay and Dirty PCBs offer, but we don't want our competitive edge to be based solely on price. So, it would be super helpful if all you fine people could give me a little bit of feedback:

• What do you find most frustrating about ordering PCB boards online today?
• What are the major factors that affect your decision with regards to manufacturing your boards (eg: cheapness, quality, customer support, processing speed)?
• What's the typical size of the board you normally order?
• What would be a helpful feature that you would like to see on a PCB order form and/or site?

Any input you guys can provide would be super helpful!
 

[691175002]

I would prefer that they not add text/identifiers to my silkscreen, although I understand that it probably makes the job easier.

[Probb]

The fab houses we work with etch production identifiers into the surface finish of the PCB. You have to make a serious effort to even see them. Otherwise, the board design, specifically the silk screen, is totally un-modified by the manufacturing processes. Is this what you're after?

[ataradov]

What do you find most frustrating about ordering PCB boards online today?

Given how cheap boards are, shipping prices become a significant part of it. So if you can lower that somehow, it would be nice.

What are the major factors that affect your decision with regards to manufacturing your boards (eg: cheapness, quality, customer support, processing speed)?

Price most of the time. I have not had quality problems in recent years.

What's the typical size of the board you normally order?

Up to 10x10 cm.

What would be a helpful feature that you would like to see on a PCB order form and/or site?

OSHPark-like gerber render preview. I use OSHpark for that, even if I don't end up using them for the actual boards.

And yes, visible manufacturing marks are annoying, especially if some surfaces are made to be front panels, and you have to additionally specify where they can and can not place those marks, and then worry if they will screw up.

[mrpackethead]

• What do you find most frustrating about ordering PCB boards online today?

Dealing with any 3rd party that lengthen the supply chain between me and the people actually doing the work.   If there is an issue, i want to hear it first hand, so it can be resolved as fast as possible.

• What are the major factors that affect your decision with regards to manufacturing your boards (eg: cheapness, quality, customer support, processing speed)?

The days of ugly bad quality pcbs are largely gone. this is a commodity item and most do it well enough for the normal run of the mill stuff.   ( FR4 2/4/6/8 layer )...

• What's the typical size of the board you normally order?

typically i'm running boards as panels.    Particaully for the simple stuff that is low cost.  At prototyping stage this lets me not only verify the circuit, but the panels manufuacturablity.   ( you want to make sure all yoru tooling is 100% before you order 500 panels.   I try to keep the panels to smaller than an A4 page.. This makes it workable at paste and assembly.

• What would be a helpful feature that you would like to see on a PCB order form and/or site?

Somethign you might be able to do for the hobby market woudl be to aggregate orders into a weekly shipment and then reship them from your local geography.. But then you limit your self to geopgraphys..

Not wanting to pour cold water on this, but in these speed of internet, highly commodistised markets, you're going to need to come up with somethign pretty special to make your offering attractive.

[Probb]

Great advice,

So, I think what your describing in your suggestion is similar to the OSH Park model, where they collect a bunch of PCB orders and make one big order mashed on a single panel to save everybody money; but you're looking for a more local or hub style to it?

[Cerebus]

• What do you find most frustrating about ordering PCB boards online today?

A complete and clear set of requirements for gerbers. How they expect board outlines, routing lines, v-groove lines to be presented etc. Every low-cost PCB fab I've ever looked at leave this stuff way too vague. Given that one is often relying on someone Chinese's grasp of English it's much better to have clear guidelines on how to present things so that they are interpreted correctly.

• What are the major factors that affect your decision with regards to manufacturing your boards (eg: cheapness, quality, customer support, processing speed)?

Low cost postage options. I'm quite happy to wait for China Post or whatever low cost carrier they use, but I don't want to pay more than I am for the PCBs for express shipping that I don't need and often attracts spurious customs fees and charges on orders that are actually below the customs limits (DHL, TNT all that crowd).

[Probb]

What's everyone's thoughts on an online order form that keeps things as simple as possible. I realize everyone has their own preference with regards to customizing their PCB order to exact specifications, but would you be more inclined to just upload your gerbers (or better yet just your .pcb or .brd files), select your order quantity, and let us handle the rest?
Here's one thing I'm currently brainstorming:
Only manufacture boards that are less than 10x10cm with 1 to 2 layers, green solder mask, HASL lead free surface finish, white silkscreen, 0.6mm thickness, and 1oz copper trace.
If your PCB design is less than or equal to 10x10cm and has no more than 2 layers, and you're cool with the way we manufacture the board (as described above), all you'd have to do is upload your design files.
I'm looking to make this site really fast and easy to use. It's more for the hobbyist who isn't too worried about very detailed board specifications, or the designer that's working through prototypes for a new design that they need to test.

[ataradov]

Only manufacture boards that are less than 10x10cm with 1 to 2 layers, green solder mask, HASL lead free surface finish, white silkscreen, 0.6mm thickness, and 1oz copper trace.

That's exactly what PCBWay is doing for $5/10pcs. How are you going to compete with that? The shipping is $20-30, which is a killer for single orders. So I typically just make 3-5 boards at a time, and then make an order. This requires some non-linear thinking, but generally works.

Ordering process is not particularly hard with any popular PCB manufacturer. I don't think it is such a huge problem to figure out ordering form for a person that figured out EDA package .

[Probb]

Hahaha very true.

[mrpackethead]

Only manufacture boards that are less than 10x10cm with 1 to 2 layers, green solder mask, HASL lead free surface finish, white silkscreen, 0.6mm thickness, and 1oz copper trace.

That's exactly what PCBWay is doing for $5/10pcs. How are you going to compete with that? The shipping is $20-30, which is a killer for single orders. So I typically just make 3-5 boards at a time, and then make an order. This requires some non-linear thinking, but generally works.

Ordering process is not particularly hard with any popular PCB manufacturer. I don't think it is such a huge problem to figure out ordering form for a person that figured out EDA package .

You can nromally also select a lower cost shipping ( china Post ) they just take a while to get to you..   it can be in teh region of $5-10

[jolshefsky]

• What do you find most frustrating about ordering PCB boards online today?
• What are the major factors that affect your decision with regards to manufacturing your boards (eg: cheapness, quality, customer support, processing speed)?
• What's the typical size of the board you normally order?
• What would be a helpful feature that you would like to see on a PCB order form and/or site?

#1 problem is that there is often no information about country-of-manufacture. I know most people only care about price, so I'm the only one who cares about worker rights/safety.

#2 problem is lack of design rules. Track width is nice, but what is the drill size list? How much actual clearance from the edge? What's the feature size on the silkscreen?

I generally order either small-ish boards (around 10cm^2) or very very small boards (<5 cm^2). Price, within reason, has a far lower priority than getting boards back that work. Even though the low-volume stuff is for hobby/prototyping, broken traces and other junk just wastes my time.

[Probb]

Great feedback Jolshefsky,

So, would a page dedicated completely to the manufacturing rules of the fab house be helpful; eg: full list of drill sizes, minimum trace spacing/width, edge clearance, etc.?

[ataradov]

But if you are using a "handful of Chinese fab houses", how do you plan to get all that info and make sure it is consistent?

[janekm]

Frankly, now is a terrible time to try to enter this market as an agent. A few years ago it was quite popular for agents to set up in Shenzhen and offer an interface for International customers to order and pass it on to the local prototyping PCB factories. It made sense because the PCB factories didn't want the hassle of Chinese export regulations (and smaller agents can somewhat skirt around that so long as the volumes aren't too huge).

Now that you have factories offering the service directly like PCBWay brand is doing, there's very little opportunity left. They have located their factory inland for cheaper labour and land prices, and aren't going to be leaving any margin for you. For the moment there's perhaps still the DHL fee (which would be really hard for you to work around) but there are already shipment consolidation services that can get that cost down, so there's room for PCBWay to get prices on shipping down easier than for you.

[Probb]

Ataradov,
We've built a network with a handful of Chinese fab houses, but once we've built a solid business model, we'll only be working with one house that suits our model best.

Janekm,
Great feedback. I realize when it comes to price, it's going to be next to impossible to beat out the big players. That's why I'm trying to get a little more information with regards to what these guys might be missing or what could be added to make the overall experience of ordering PCBs more enjoyable, if that's possible haha.

[Harvs]

What I really want out of a PCB fab now is to have somewhere that I could build a working relationship with to reliably get the outcome I need.

I do a lot of design to final prototype stage as a contractor for other companies that handle their production.  I'm not ordering bargain priced boards, usually it's either 2-layer boards with fast turn or spec'd up multi-layer boards.

So what I am finding a problem is Chinese boards housing screwing orders up.  It's like every third or forth order they do something stupid, some examples:
- Just last week PCBway failed to ship an urgent 24hr turn board for 72hrs.  They didn't tell me about it until I wrote to them after seeing the DHL date, then they said they were one board short on an order of 50, so instead of sending them (which would have been ok) they added the extra board to another slower run then sent them all three days later!  They then offered to refund the 24hr turn fee only (to me this seems like a calculated decision rather than a genuine mistake.)

- I had an order for 5 reasonable sized 6 layer boards from PCBCart. They came with solder mask imperfections and bent in all sorts of weird ways.  I asked about why they were bent because it made soldering a large BGA a problem. They claimed it was my design that was the problem (which is fine if it is) but then refused to tell me what was wrong with my design and would only give general completely useless advice despite multiple emails.  Most likely it was some other designs in the panel that caused the issue but they didn't want to admit it.

I could go on and on with examples from several large board houses but I'm not just trying to have a rant.  The market segment I'm missing is something between the very high prices of western board houses and the lack of reliability from Chinese board houses.

[ChristopherN]

What do you find most frustrating about ordering PCB boards online today?

I usually order boards that I need quick. It sucks that many pcb houses lie about the actual delivery time to my door (which is what I care about). I usually don't care if the board or shipping is a few bucks more or less.
An example: 10 pcbs, 100x100mm:
Multi Circuit Boards: 2 days production + 1day shipping: 250€ (and they hold their promise).
PCBway: 24h production (which can be higher due to the weird order process and manual check they do) + DHL Express (up to 3 days) from China to Germany: $62

I would happily pay 120€ to get the boards in 3 days.

Another big plus would be to be able to use files directly out of Circuit Studio or Eagle. And it would be nice to get pictures of your pcbs in the production process as some other pcb houses offer.

What are the major factors that affect your decision with regards to manufacturing your boards (eg: cheapness, quality, customer support, processing speed)?

Speed and ease to order.

What's the typical size of the board you normally order?

Min 8*12mm (in a panel with tabs), max 200*200mm

What would be a helpful feature that you would like to see on a PCB order form and/or site?

Direct cad imports from CircuitStudio and Eagle.
Photos from production.
Stencils.
Real invoices that match the local regulations of customers.
Honest customs forms.
Good packaging, had a bent stencil once.
More payment options (PayPal!).
More high-end shipment options, there are different classes in express shipping.
More languages on the web interface.
Specifications for the materials used (MSDS!)

I guess my requirements are a bit on the demanding side and not at all easy to solve, but I think that there is a market "in the middle".

[alexanderbrevig]

Clear DFM rules.
Clear and sensible gerber rules.
Online gerber viewer (absolute final inspection, more than once have I found a revision silk marker needs an update ).
Ability to order stencils.
For me I would like a sane price between ten and a thousand pieces.
Sane defaults. Once I got brown on black without changing any colors.
Let me know of you det something up. I'll try it!

[jolshefsky]

Great feedback Jolshefsky,

So, would a page dedicated completely to the manufacturing rules of the fab house be helpful; eg: full list of drill sizes, minimum trace spacing/width, edge clearance, etc.?

For production, I have stuck with Advanced Circuits. Their specifications page (including the "full list") is more than complete, including specs I don't even know what they mean.

Even they don't specify the drill sizes which was annoying when I wanted a plated hole for press-fit: Mill-Max says they want a 0.026" (0.66mm) hole (without tolerances which I take to be ±0.001" (±0.03mm) or so). Advanced Circuits says ±0.003" (±0.08 mm) typical (they recently added ±0.002" (±0.05mm) for press-fit applications) but even at the best, that's a big ±8% error. I decided to put in two holes to mitigate risk: 0.026" (0.66mm) and 0.025" (0.64mm) which actually get manufactured different sizes. I'd rather not guess whether they are using 0.026" and 0.025" drills, or 0.7mm and 0.6mm drills, or laser-cutting the small holes.

Unrelated to that, I do think there is space in the market for small runs of higher-than-hobby quality. Sometimes I'll need 100 small boards for a "run", but with a setup cost of $400, the boards are practically free so I end up buying 400 instead.

[ansonbao]

- Just last week PCBway failed to ship an urgent 24hr turn board for 72hrs. 

We have noticed this problem and are working on it,thanks for your feedback.

[Probb]

This is all great feedback guys! Really appreciating it.

[free_electron]

here is what i often find lacking

- 10 mil drill
- 5 mil track and gap or even 4 mil track and gap
- milled slots ( especially for those DC jack lugs.)

the ability to order the entire panel. or two half panels or 4 quarter. ( a panel is a bit big for shipping ... )

the idea is : you give me a working area. inside this area i am allowed to do whatever  i want. this area is placed 2 times on a panel or 4 times on a panel( typically 18 by 24)
i receive my design milled to the working area.

this allows me to send boards through a pick and place as a panel (opposed to little thingies that are hard for the line to handle )

[Probb]

How many of you guys prefer panelizing your designs versus ordering independent boards?

[ChristopherN]

Depends on the board size and everything that follows. I order small boards as panel, it would be a pain to handle small boards alone. I usually don't care for larger boards (starting from 5x5cm), but I mainly do very small runs and hand assembly.

Another service that would be nice is to be able to let you put QR-/Barcode stickers (with my content / code) on each board.

[hcglitte]

I would like to know stackup and dielectric constants between all layers for all combinations of thicknesses and layer count.

And I would like to be sure that when I do a reorder one year later that I get the exact same stackup.

[mrpackethead]

How many of you guys prefer panelizing your designs versus ordering independent boards?

Definenatively want to panelize my own, so i can optimise it for my production... This means a 7mm tooling strip on the two long edges.  4x 3mm holes at 5mm in from each corner.  Fiducal Marks for  (a) stenciling,  (b) PNP aligment..   (c) bad block notification..   The tooling strip also lets you have a place to put layer checks, a place for the fab to put any marks they need.    The above is very specific to how i'm set up and is not for everyone.  By optimising for your own set up you make life much much easier for yourself.   I also know how all the panelisation is set up, so creating PNP files is easy.

[Probb]

Big thanks everyone for the feedback. I'm going to do my best to incorporate some things I think could be really beneficial based on what you've all told me. I'll let you all know when the site's launched.

[KL27x]

Website is important to me.

I want all my account information to be clear and easy to navigate. My quotes, my previous orders.

Reordering should be a click.

I should be able to change quantity of a previous order and submit for quote and lead time with a click.

I almost always want my orders in panels. This should be an option.

My current fab gives 24 hr chat support. But honestly, this is not that big a deal to me. If I need fast support, I will go with someone that has it, but for my day in/out I just want to be able to do everything I need through a web interface.

In short, I want a slick web interface and accurate lead times, and I should almost never have to talk with anyone. I speak Gerber and dollars.  If shop is busy, I want that to be reflected in estimated lead times. If holiday is upcoming, I want that to be reflected, as well. Lead time should be accurate as possible and updated as necessary.

[alanambrose]

Maybe there is a niche in the non-rock bottom stuff - say smaller drills, 6 layer, flex, solder mask between 0.5mm pins etc. I get that 6-layer is more expensive - but 4x the cost of 4 layer?

Alan

[janekm]

Maybe there is a niche in the non-rock bottom stuff - say smaller drills, 6 layer, flex, solder mask between 0.5mm pins etc. I get that 6-layer is more expensive - but 4x the cost of 4 layer?

Alan

I don't think so. The whole concept of low-cost PCB manufacturing is based around pooling customer orders as much as possible. Once you need 6 layers you're also likely to need other specialised options (impedance control, micro-vias, custom stackup) which ruins any pool-based model. Also, in all my years of designing PCBs I have never yet designed a 6 layer PCB, and probably 90% 2-layer, 10% 4-layer. From what I see from others it's very similar. A 6-layer PCB usually takes a much longer time to design as well, so the market is just never going to be as large.

[AxelVoitier]

For me a killer would be mid-range at nicer prices.

Mid range being for medium density: 2 layers with QFN/QFP and small (max 16 pins) BGAs, 4-5 mil min. tracks/space, 0.1 mm min. solder mask, ENIG, 0.2 mm drill, etc.

Currently there is a big jump from the ultra low cost (max 100x100mm, leaded-HASL, 6-mil track, 0,4 mm min. solder mask, 0.3 mm drill) and that mid-range.

Or at the very least something better on the ENIG and min. solder mask side of things. That would be sufficient to fully unlock the next level of SMD designs hobbyist could practically do at a lower cost.


For shipping cost, it's true that for just a few boards of one design it can be expensive (especially for the ultra low-cost range where hobbyist can just etch themselves to have them faster). But if you support having multiple designs per shipping that can be fine (but your website would need to find a way to promote clearly that way of functioning to lower the shipping costs).

What could also help in such configuration is to allow for different fine grained quantity combinaisons of the different designs (because for the first prototype iterations it is not that often you needs these 5 or 10 pcs... and that feels like a waste after a while). And just bill on the total area used (with min. area if you want, like today we have min quantity). In short: I do understand the fab needs minimum board area for the pooling concept to work. But just let me decide how to spread my uses of that area over different designs of low-volumes prototypes. Of course assuming all the designs use the same panel options.

[KE5FX]

The market segment I'm missing is something between the very high prices of western board houses and the lack of reliability from Chinese board houses.

What he said.  Cost is no longer a problem at all, once you stop using US board houses.  There's no room at all for you to undercut the prices I'm seeing from offshore board houses, but on the other hand, I'm always interested in services that cost a bit more but offer more options, better quality, and higher consistency and reliability.  As hcglitte suggests, stackup consistency from one order to the next is very important.

The central problem is that the Chinese direct sites like allpcb.com only have to get a little better before they leave no room for improvement at all.  You're definitely entering a race to the bottom.  Have a plan for what to do when you get there.

[KE5FX]

A 6-layer PCB usually takes a much longer time to design as well.

Yeeeaaaahhhh.... no. 

[mrpackethead]

Also, in all my years of designing PCBs I have never yet designed a 6 layer PCB, and probably 90% 2-layer, 10% 4-layer. From what I see from others it's very similar. A 6-layer PCB usually takes a much longer time to design as well, so the market is just never going to be as large.

Im more like 80%, 4 layer, 10% 2 layer, and 10% more than 4 layers.    4 layer pcbs are considerably cheaper to design than 2 layers, result in tighter and often much better results.

[mrpackethead]

The market segment I'm missing is something between the very high prices of western board houses and the lack of reliability from Chinese board houses.

What he said.  Cost is no longer a problem at all, once you stop using US board houses.  There's no room at all for you to undercut the prices I'm seeing from offshore board houses, but on the other hand, I'm always interested in services that cost a bit more but offer more options, better quality, and higher consistency and reliability.  As hcglitte suggests, stackup consistency from one order to the next is very important.

The central problem is that the Chinese direct sites like allpcb.com only have to get a little better before they leave no room for improvement at all.  You're definitely entering a race to the bottom.  Have a plan for what to do when you get there.

In deed.  there product is actually pretty acceptable in 95% of cases. Where the let down is this mismatch of expectations and/or information.     If you want to sit in that space and get that right, theres a market.  becuae that is the ONLY value proposition that is left.  But watch out the chinese are getting better at it.

[Probb]

Awesome feedback everybody, it's really appreciated! We're taking a lot of your comments into serious consideration and trying to make a solid overall solution that incorporates everyone's ideas.

Here's a quick update (keeping things short and sweet):

• In terms of keeping costs down, we realize shipping is the big killer. So, we're working on the logistics to create a pooling system that ships multiple orders to a single location (in multiple areas) for pick-up
• We're developing an order form that is really fast and simple to use with links to all of our manufacturing details so you clearly understand what our limitations are (trace spacing, drill sizes, etc.)
• Our site will be member based, so you'll be able to track order history and simply click on previous orders and select a quantity to make an order for an older board you designed and previously made.
• We're working to make 4L and 6L board processes inexpensive while maintaining high output quality
• We're also working to keep prices low for board quantity orders over 10
• DISCOUNTS GALORE! (More details to come)
• The beta site should be up and running in about a month (+/- a couple weeks).

Keep the feedback coming (positive and negative) - it's been extremely helpful!

[Probb]

Hahaha we're in the process of working out all the kinks. The uncertainties will be gone the day we launch

[Probb]

evb149 mentioned something about being able to order PCBs + stencils + front panels + enclosures  in a sort of combined package. Does anybody else see a benefit to this? I like the idea of getting custom enclosure's developed based on common PCB sizes and including it in a PCB order, but I don't want to push to far outside of a particular niche (you can only add so much before things get messy); however, there might be something more to this. Thoughts?

[ataradov]

Forget the PCBs. If you could start a service of just making custom (customized) enclosures, it would be great on its own. Getting things machined in plastic in the US is prohibitively expensive, and foreign companies want a huge order before they do anything.

[Cerebus]

The beta site should be up and running in about a month (+/- a couple weeks).

25%+ uncertainty? This will drive those volt nuts here nuts !

Your error analysis is off. "about a month" could mean everything from 29-31 days (German "about"), one to three months (in a mañana or insha'Allah culture) to three months to a year (rural Ireland*). So I make that an error margin of -100%/+1200%.


* Paddy: So what does 'mañana' mean?
Juan: That I'll get around to it when I do.
Paddy: Oh, we have a phrase like that back in Ireland. Only it doesn't contain the same sense of burning urgency as 'mañana'.
Juan: What's the phrase?
Paddy: "I'll do it tomorrow."

[jmelson]

I had a customer specify that a board needed to come in a nice box.  I found a very affordable extruded aluminum box at Newark, about $10 in single quantity.
I machined one end plate for connectors, and found a DIN rail adaptor for it.  But, the end plates were hard anodized, and I ended up breaking one solid carbide end mill per cover, more or less!
Yikes.  I think the fix, if I ever did that again was to throw out the cover that needed machining and machine new ones from NON-anodized aluminum and cover them with a label.

Jon

[asmi]

+1 to making midrange 4-6 layer boards more affordable. I don't mind waiting a week or two before shipping if it would make these boards cheaper. New Allpcb.com service sounds great except they they emphasise speed, and for some bizarre reason they charge $8.695 for each BGA part you've got on the board. Other than that they offer good prices, and is the only manufacturer I know of that offers cheap "Controlled Impedance" option (only $17.39 for 4-layer board).

[KE5FX]

New Allpcb.com service sounds great except they they emphasise speed, and for some bizarre reason they charge $8.695 for each BGA part you've got on the board.

Even if you don't order assembly service?

[asmi]

Even if you don't order assembly service?

Yep. Check out their new ordering page - there is a field at the bottom where you're supposed to type in number of BGAs in your design. I wonder what they were thinking when they've introduced this surcharge - I can't think of any reason to use 6-layer boards other than breaking out large BGAs...

[ataradov]

They just want to pad the price. In the end PCBWay is cheaper than AllPcb all around. I fell like they just want to convert AllPcb into a premium service.

[asmi]

They just want to pad the price. In the end PCBWay is cheaper than AllPcb all around. I fell like they just want to convert AllPcb into a premium service.

Not for 6-layer boards. Even with added costs of 4 BGAs 0.125/0.125/0.25 mm boards with 50 Ohm CI (minimum for 0.8 mm BGAs like DDR2/3/3L) are cheaper in allpcb. PCBWay pricing for that kind of board is weird - price with CI is less that without CI

[ataradov]

Not for 6-layer boards.

Don't judge allpcb price by the instant quote. They will bump it by a random amount after you already paid, and ask you to pay more. At least that's what they did to me on a pretty simple board.

And oh yeah, refunds don't go back to PayPal, they go towards store credit.

[asmi]

Don't judge allpcb price by the instant quote. They will bump it by a random amount after you already paid, and ask you to pay more. At least that's what they did to me on a pretty simple board.

I used their service few times (admittedly before they've dumped subcontracting business and became a manufacturer), and what you're describing only happened once, and even then we quickly resolved situation to my satisfaction. So I can't say anything bad about them from my experience - other than they don't seem to support Gerber x2 format and work with older one.

[Kean]

Additional cost per BGA could be related to e-testing.  They might have to use a higher spec flying probe machine for some BGA pad layouts.
That additional cost seems somewhat exhorbitant though.  I imagine they want to always cover costs (+ a good margin) on these more advanced designs ... while they still can.

[asmi]

Additional cost per BGA could be related to e-testing.  They might have to use a higher spec flying probe machine for some BGA pad layouts.

In this case it would be a flat fee, and I would be OK with that (as long as it's reasonable). But per-package fee is something really weird.

[GreggD]

Options for UL markings and certificate of conformance.

[asmi]

It's common in China that they charge you not only based on their cost, but also on your estimated profit from their service. Basically more BGA means higher tech, and higher tech means more profit.
By this way, they can offer lower cost to low tech DIYers to spread their name, and recoup the cost from established high tech corporate customers.

Well my profit from my boards is zero. I'm totally willing to share that profit with them if they so desire. Damn, I can give them the whole 100% of that profit!

[asmi]

For that case, PCBWay has an sponsorship discounting. Basically you sign an agreement with them stating your PCB work is not funded, and you agree to provide them with a photo including your acknowledgement to their service and your final physical board. They can give you a heavy discount.

Check out here: https://www.pcbway.com/project/sponsor/

There are some really cool projects.

I looked at that, and they seem to require photos of the project before getting sponsorship. But how am I supposed to have them, if I don't have the board?

[NorthGuy]

I want to add my vote for more layers (6, may be even , better specs (4-5mil traces/8-10mil drills), ENIG. There's plenty of places where you can order low-end, but it is real hard to find a manufacturer for reasonably priced 6-layer boards with good specifications. Even if it's small and you only need one or two, you'll end up paying $300 or more. This is a huge room for price improvement here.

[asmi]

I want to add my vote for more layers (6, may be even , better specs (4-5mil traces/8-10mil drills), ENIG. There's plenty of places where you can order low-end, but it is real hard to find a manufacturer for reasonably priced 6-layer boards with good specifications. Even if it's small and you only need one or two, you'll end up paying $300 or more. This is a huge room for price improvement here.

Allpcb now offers 5 6-layer boards 100x100 mm 0.125/0.125 mm trace/spacing 0.25 mm drill, 50 Ohm CI, ENIG for only $200. But they charge $8.695 per each BGA device you've got on the board They also offer 4-layer boards with the same specs for $95.76.
So we're slowly getting to the point where 6 layer boards are a viable option for hobbyists. 4-layer board already are totally viable, especially if you can make do with "default" 0.15/0.15/0.3 process.

[mrpackethead]

Been discussing this bga malarkey with them.. And they are are looking at it.

[NorthGuy]

WellPCB offers 1.2mm, 6L 6 mil drill with 3mil track/spacing and ENIG boards at $195/5pcs plus $2/pcs, for size of 50mm*50mm. They also offer ultra thin technology, down to 0.35mm/4L and 0.55mm/6L.

Thanks. These guys offer really good prices.

For some reason no one publish their stack-ups

Quote form is strange. If I select 3-4 mil option, the form says +10%, but price goes up dramatically. They also don't say what are the specs if you don't select "3-4 mil".

Will need to email them.

Allpcb now offers 5 6-layer boards 100x100 mm 0.125/0.125 mm trace/spacing 0.25 mm drill, 50 Ohm CI, ENIG for only $200. But they charge $8.695 per each BGA device you've got on the board They also offer 4-layer boards with the same specs for $95.76.
So we're slowly getting to the point where 6 layer boards are a viable option for hobbyists. 4-layer board already are totally viable, especially if you can make do with "default" 0.15/0.15/0.3 process.

Thanks for that too. WellPCB looks more promising though. But devil is in the details

Perhaps prices are going improve soon!

[asmi]

For some reason no one publish their stack-ups

Quote form is strange. If I select 3-4 mil option, the form says +10%, but price goes up dramatically. They also don't say what are the specs if you don't select "3-4 mil".

Will need to email them.

Their form is weird to say the least. For example, you can't select CI and 3-4 mil traces (wtf is that btw? is it 3 mil or 4 mil?) at the same time. If you will find out - please let me know. Also I wonder what would it cost to have a custom stackup, as all default stackups I've seen to far sucks for 50 Ohm traces unless you're OK with going to thinner PCB. And that is dangerous for big BGAs as they can easily crack if PCB is too "bendy".

Thanks for that too. WellPCB looks more promising though. But devil is in the details

And there are indeed "details". 4 times smaller area (I might suck at layout, but in my design just DC-DC converter to supply FPGA power takes up about 3x5 cm area), also standard TG-130 will not fare well under Lead-free reflow temperatures (PCBWay, for example automatically, upgrades board to TG150 for 4 layers and above).

Perhaps prices are going improve soon!

I can't wait for that to happen. But for now we're seem to be stuck with ~$300 per five 10x10 cm PCBs. PCBWay seems to offer no-cost custom stackup and via-in-a-pad options - at least their calculator says so, not sure if it's actually correct as it also shows non-CI boards much more expensive than CI ones, as well as 5x5 cm boards being twice the price of 10x10 cm ones, none of which makes any sense whatsoever. I kinda suspect that it's just broken for these kind of boards, but for now I'm trying my very best to stick to 4-layer boards to save money. I know there is PCBWay representative here on the forums, maybe he/she would be kind enough to shed some light on this madness.

[KL27x]

Additional cost per BGA could be related to e-testing.  They might have to use a higher spec flying probe machine for some BGA pad layouts.

In this case it would be a flat fee, and I would be OK with that (as long as it's reasonable). But per-package fee is something really weird.

I don't see it this way. The prices they give aren't exact. Based on the same area of board, same minimum pitch, components, vias.... essentially every possible spec that can be input into a quote algorithm.... one customers board can be a lot less profitable than another, due to MORE of the board being minimum pitch and/or having more traces, overall.  Presence of BGA can potentially be closely associated with the manufacturing cost (lower yield). In fact, if looked at this way, it might be generous that there is a flat per-unit fee, rather than and exponential one.

So if presence of a BGA (statistically, on average) increases chance for failed board by 10% (on average), putting half a dozen of them on 1 board means they make and test twice as many boards as you order and end up throwing half of them away.

Personally, I try to make my board manufacturer-friendly. In case I repeat order a lot of them, I can ask for a new quote/discount. If you "abuse" the minimum clearances to get the tiniest board possible to save a few cents, you will save money in the short run, based on the flat-pricing model, but you wlll not be a favorite customer, lol.

[asmi]

I don't see it this way. The prices they give aren't exact. Based on the same area of board, same minimum pitch, components, vias.... essentially every possible spec that can be input into a quote algorithm.... one customers board can be a lot less profitable than another, due to MORE of the board being minimum pitch and/or having more traces, overall.  Presence of BGA can potentially be closely associated with the manufacturing cost (lower yield). In fact, if looked at this way, it might be generous that there is a flat per-unit fee, rather than and exponential one.

Why would you want a 6 layer board if not for BGAs? I just don't understand this.

If presence of a BGA increases chance for failed board by 10% (on average), putting half a dozen of them on 1 board means they make and test twice as many boards as you order and end up throwing half of them away.

Can you please provide your source for 10% data point? It seem weird to me as BGA pads are usually larger than some other parts' footprints (like 0.2x0.2 mm pads of BME280 sensor), yet they didn't change anything extra from me for that... It just doesn't add up.
The theory posted above (about ripping off "perceived profit" off customers) at least makes some sense, but I just don't see a relationship between amount of BGAs and "profitability"/"high-tech"-ness of the board. Afterall, most SoC boards usually only contain two or three BGAs (main one for the SoC itself + 1 or 2 DDR3 devices), and these boards are definitely "high-tech".

[KL27x]

I am not sure what 6 layer issue is. I was only commenting on additional cost per BGA. Personally, every PCB I have ever seen with BGA on it, the density of components and microscopic caps/resistors is highly associated and localized around said BGA. To me, it seems logical that based on manufacturer's own statistics that each BGA could cost the manufacturer money/profit if they stick only with their "automatic quote machine," without exception.

The 10% is just theoretical. Pulled out of a hat for sake of argument.

In making my own boards, for instance, it is easily observable over time that yes, I can do 6/6 where absolutely necessary. But the more of the board I want to cover with this kind of pitch, and the larger the board, the more I can expect failure. One failure in a tight pitch area on a huge board still equals huge piece of garbage. Vs 1 mistake on panel of 10 smaller boards means 90% good boards.

If you order your boards on a panel, you will find that even large pitch very simple boards have a failure rate. This is a real cost in material and time and work.

[asmi]

I am not sure what 6 layer issue is. I was only commenting on additional cost per BGA. Personally, every PCB I have ever seen with BGA on it, the density of components and microscopic caps/resistors is highly associated and localized around said BGA. To me, it seems logical that based on manufacturer's own statistics that each BGA could cost the manufacturer money/profit if they stick only with their "automatic quote machine," without exception.

The 10% is just theoretical. Pulled out of a hat for sake of argument.

The "microscopic-ness" of caps for BGA decoupling is more related to BGA pitch than it is to amount of them. If they can't even reliably produce 0402 pads, they probably do not deserve to still be in business at this day and age.
But they can, and we all know that. Another curious thing - every other PCB fab I've ever used didn't not give a crap about what's actually on the board. allpcb is the first and only that I know if (so far) that does that. If this is caused by them having too many failures - I would probably serve myself well to steer clear of them and instead take my business to other fabs who are certain about their manufacturing abilities.

[KL27x]

In making my own boards, for instance, it is easily observable over time that yes, I can do 6/6 where absolutely necessary. But the more of the board I want to cover with this kind of pitch, and the larger the board, the more I can expect failure. One failure in a tight pitch area on a huge board still equals huge piece of garbage. Vs 1 mistake on panel of 10 smaller boards means 90% good boards.

If you order your boards on a panel, you will find that even large pitch very simple boards have a failure rate. This is a real cost in material and time and work.

It's not as simple as a manufacturer can do up to X pitch or not. There's a curve and an associated cost. Period. It's not a matter of my process is more accurate, so I can do this 100%. They must dedicate more time, experienced workers, and loss in yield rate for tighter pitch boards with higher pad counts. And there is probably a fairly strong association to presence of BGA.

Just because one manufacturer has this extra charge and another does not, this does not mean one manufacturer is ripping you off. It means they use a different model to account for their actual costs, on average. You can game the system to find the best price; but if/when everyone does this and when BGA becomes a larger part of their business, everyone else will also start charging extra, or at least change their pricing model.

[asmi]

In making my own boards, for instance, it is easily observable over time that yes, I can do 6/6 where absolutely necessary. But the more of the board I want to cover with this kind of pitch, and the larger the board, the more I can expect failure. One failure in a tight pitch area on a huge board still equals huge piece of garbage. Vs 1 mistake on panel of 10 smaller boards means 90% good boards.

I've been sticking to 0.15/0.15 mm for the past year or so and used several different fabs (including allpcb - albeit in their "middle-man" status of the time), and I am yet to see a single failure.
0.15/0.15 is not a modern technology - it used to be "high-tech" in the past century, but those times are long gone. Heck, I've been able to produce such tracks at home with laser printer's toner with 100% success!
Nowadays modern technology is 2-3 mil traces and 0.075mm microvias. If I was to order this kind of board - then I'd accept your justification of high price. But not for 20-years old tech.

[KL27x]

If you order your boards on a panel, you will find that even large pitch very simple boards have a failure rate. This is a real cost in material and time and work.

If a company is making boards at 100% success rate, and they are maintaining this on very large orders, they are pretty dumb. A smart company would be looking at what they're wasting time and effort on.

[asmi]

If you order your boards on a panel, you will find that even large pitch very simple boards have a failure rate. This is a real cost in material and time and work.

Yes they do, and I'm not arguing with that. What I'm contesting is connection between amount of BGAs and failure rate - frankly I think it just doesn't exist. Not with 1.0 mm pitch BGAs anyway (and they charge regardless of BGA pitch and pad size!).

[KL27x]

^At some point, easy quote/pricing system will break down if you differentiate between too many specifications. Perhaps they lump them together just to make the system work.

Tomato, tomato. You have options to use whatever company you want, with whatever quotation/pricing scheme you like better. I use a few different companies for different purposes. And I ask for new quotes (I,e. discounts), perhaps once a year or so, if I order the same board.

If a company is adding an extra charge for this or that, it is probably because they do not like your business. It is not as profitable as other customers that do not need this or that. If the extra charge is a deal breaker, definitely go somewhere else. Perhaps they were getting a lot of BGA customers and too many issues. Whether due to customer ignorance/support/chat/service cost or manufacturing/testing cost, or too many low volume orders, it doesn't matter. Perhaps they are operating too close to capacity in the department that is setup to handle BGA level boards and/or this part of their business is growing too fast for them to service. So they are trying to reduce demand. For w/e the reason, they are essentially saying your BGA business is not that important to them, at least not under the original pricing scheme. Their demand is greater than they care to sell at. If you can get a better price somewhere else, please do that so we can make more profit on our other services. And if/when other manufacturers get deluged with these low profit orders, they may adjust their scheme, too.

[mrpackethead]

Additional cost per BGA could be related to e-testing.  They might have to use a higher spec flying probe machine for some BGA pad layouts.

In this case it would be a flat fee, and I would be OK with that (as long as it's reasonable). But per-package fee is something really weird.

I don't see it this way. The prices they give aren't exact. Based on the same area of board, same minimum pitch, components, vias.... essentially every possible spec that can be input into a quote algorithm.... one customers board can be a lot less profitable than another, due to MORE of the board being minimum pitch and/or having more traces, overall.  Presence of BGA can potentially be closely associated with the manufacturing cost (lower yield). In fact, if looked at this way, it might be generous that there is a flat per-unit fee, rather than and exponential one.

So if presence of a BGA (statistically, on average) increases chance for failed board by 10% (on average), putting half a dozen of them on 1 board means they make and test twice as many boards as you order and end up throwing half of them away.

Personally, I try to make my board manufacturer-friendly. In case I repeat order a lot of them, I can ask for a new quote/discount. If you "abuse" the minimum clearances to get the tiniest board possible to save a few cents, you will save money in the short run, based on the flat-pricing model, but you wlll not be a favorite customer, lol.

After queryng this with AllPCB, they have decided to remove this BGA surcharge from their quotation engine.     I think they realised it was not something that was sensible.       However as a side issue to this,  their service is'tn so suitable for using with BGAs, as they dont' go to .2mm Vias, or offer via in pads, so that makes breakign out all but the biggest pitched bgas nearly impossible.

[asmi]

After queryng this with AllPCB, they have decided to remove this BGA surcharge from their quotation engine.     I think they realised it was not something that was sensible.       However as a side issue to this,  their service is'tn so suitable for using with BGAs, as they dont' go to .2mm Vias, or offer via in pads, so that makes breakign out all but the biggest pitched bgas nearly impossible.

So it was just a money grab afterall....
Interestingly enough their spec sheet says they can do down to 0.1/0.1 mm traces, but their online quote system doesn't give that option. 0.1/0.1 mm and 0.25 drill would be enough to handle 0.8 mm pitch BGAs and up.

Hmmm. Now their quote system doesn't even allow choosing 0.25 mm drills now (it used to just a couple of days ago). BGA count field is still there, and funny enough there is a "Min BGA pads size:0.25mm" note next to it. This pad size is usually used on 0.5 mm pitch BGAs, and I would love to see how can one break it out using 0.125/0.125/0.25 mm process

[KE5FX]

After queryng this with AllPCB, they have decided to remove this BGA surcharge from their quotation engine.     I think they realised it was not something that was sensible.       However as a side issue to this,  their service is'tn so suitable for using with BGAs, as they dont' go to .2mm Vias, or offer via in pads, so that makes breakign out all but the biggest pitched bgas nearly impossible.

So it was just a money grab afterall....
Interestingly enough their spec sheet says they can do down to 0.1/0.1 mm traces, but their online quote system doesn't give that option. 0.1/0.1 mm and 0.25 drill would be enough to handle 0.8 mm pitch BGAs and up.

Hmmm. Now their quote system doesn't even allow choosing 0.25 mm drills now (it used to just a couple of days ago). BGA count field is still there, and funny enough there is a "Min BGA pads size:0.25mm" note next to it. This pad size is usually used on 0.5 mm pitch BGAs, and I would love to see how can one break it out using 0.125/0.125/0.25 mm process

Their quote system has always been sort of messed up in that regard.  When I was playing with it last, the price increased non-monotonically as I specified smaller feature sizes.

[Corporate666]

It's been a month since Probb replied on the thread, so I am not sure if he's actively reading - but in case any other PCB manufacturers are, here's my thoughts (worth what you paid for them)

-I think there's a couple of different groups of people ordering.  Hobbyists and professionals.  Nothing wrong with either group, but I would imagine the former tends to need more hand-holding and you work harder for the profit than with business customers. 

-There are countless companies offering PCB services, many of them specialize in cheap.  I have a small business that manufactures boutique electronics products and I don't care about cheap.  Well, what I mean is that PCB's are so cheap nowadays that if a 10cm x 10cm board is $1 each in 100pcs quantity ($100 total) at one PCB manufacturer, I really couldn't care less if another PCB shop is charging $130 for the exact same board.  Because getting bad boards or sub-par boards is so detrimental to me, that I am MORE than happy to pay that 30% premium to get good boards.

The problem is - ALL of these PCB fabs claim their boards are top notch.  So how do you really know you're getting higher quality for a higher price?

As with many other products, it's good to just tell the customer right up-front what your market differentiator is.  If you are higher price, higher quality... don't be afraid to say so.  Many of us *want* higher quality and are willing to pay more. 

Another important thing to me - lots of options!  If a PCB fab has things like tented vias, thermal-resin filled vias, metal core PCB's, flex PCB's, peelable soldermask, custom colors for solder mask, offers panelization, offers stencils (ideally framed and frameless), offers options for manufacturing time (at a price premium) and shipping, offers immersion gold, hard gold, HASL, lead-free and other options... and lets me choose various board thicknesses, materials and such - well that is a fab plant I can grow with.  Some people will always be hobbyists - and that is fine - but I think a lot of people have a goal to commercialize their designs.  I would rather have a go-to fab shop that can do all the stuff I might need tomorrow as well as the cheap and easy stuff I need today.

I may be in the minority there, but that's what happened to me over the years.  I started with 2-layer, 1.6mm boards with HASL and green soldermask.  I used to use Olimex then - that was about 15 years ago.  Now I have a PnP, I stencil paste my boards, I've done metal core, multi-layers, thermal resin vias, metal plugged vias, blind/buried vias, various soldermask and silkcreen colors and flex boards.  I only used Olimex to start because they were easy (could just upload an Eagle file).  But I remember them going back and forth with me by email about some errors on my board.  I had no idea how to make Gerbers back then.  But I outgrew them, and the subsequent PCB manufacturers are the ones that got thousands of $$ per year from me for multi-thousand piece board orders, not Olimex.

[mrpackethead]

The problem is - ALL of these PCB fabs claim their boards are top notch.  So how do you really know you're getting higher quality for a higher price?

Price is NO indicator.. The cheaper fab might actually be better.   The only way you can find out is to try them out...     And its the 'total' quality that you've got to take into account. thats ontime delviery, easy to use.. If i have to spend hours sorting out drama because its too hard,  then it coudl be free, but it woudl still be expensive if that makes sense.      I've found that for all my 'basic' PCBs ( thats stuff that is 4 layer, .15/.15 and .3mm min vias ) that AllPCB have done a really good job.   Mostly on time, they ahve owned their mistakes and they are easy to communicate. It took a bit of time to work otu what they were about though, and all their changes dont' make it easy.

[asmi]

Their quote system has always been sort of messed up in that regard.  When I was playing with it last, the price increased non-monotonically as I specified smaller feature sizes.

Yea no kidding. 6-layers all default - $83.72, change finish to ENIG - $196.90! Boom! 

[NorthGuy]

Yes it is very annoying and sad when you change ONE LITTLE THING from defaults almost no matter what that is and all of a sudden the price goes WAY WAY WAY up disproportionately beyond any reasonable cost for a PCB of those specifications.

Yes, I find it annoying too. It is not as bad when you go to quantities. Then the difference is quite modest. But if you just want few for the prototype, it's just ridiculous. And they all apparently use the same software for quotes and they all have this pricing "feature".

OSHPark is by far the best for small boards in small quantities.  Quality is excellent. They have reasonable stackup for 4-layer boards and ENIG. And their tolerances are good for 0.8mm BGA (5 mil trace and 8 mil drill). I've just made PIC32MZ DA test board and it turned out great. I paid only $40 with free shipping! They don't have 6-layer though, and everything which is bigger getting pricey.

[asmi]

OSHPark is by far the best for small boards in small quantities.  Quality is excellent. They have reasonable stackup for 4-layer boards and ENIG. And their tolerances are good for 0.8mm BGA (5 mil trace and 8 mil drill). I've just made PIC32MZ DA test board and it turned out great. I paid only $40 with free shipping! They don't have 6-layer though, and everything which is bigger getting pricey.

Are you sure about that? Their website says 5/5 traces with 10 mil drills and 4 mil annual ring - you can't breakout 0.8 mm BGAs with that process: 32 (=0.8 mm) - (10+4*2)= 14 mils between vias, which is 1 mil short (in reality a bit more, because I rounded 1 mil down to 0.125 mm, while it actually is 0.127 mm) of 15 mils (5 mil track + 2*5 mils spacing) needed to route a track between vias. Unless breaking out just outer 3 rows is good enough for you.

[NorthGuy]

Are you sure about that? Their website says 5/5 traces with 10 mil drills and 4 mil annual ring - you can't breakout 0.8 mm BGAs with that process: 32 (=0.8 mm) - (10+4*2)= 14 mils between vias, which is 1 mil short (in reality a bit more, because I rounded 1 mil down to 0.125 mm, while it actually is 0.127 mm) of 15 mils (5 mil track + 2*5 mils spacing) needed to route a track between vias. Unless breaking out just outer 3 rows is good enough for you.

I broke out every pin. You're right they have 10 mil drills, but annular rings are 4 mil, so it boils down to the same size of via pads - 18 mil. I cheated and made them 17 mil, and it worked just fine. Of course, it is impossible to see because it is on the inner layers, but here's how it looks from the top. You can still see some 17 mil vias with holes although even these are under the solder mask.

[asmi]

I broke out every pin. You're right they have 10 mil drills, but annular rings are 4 mil, so it boils down to the same size of via pads - 18 mil. I cheated and made them 17 mil, and it worked just fine. Of course, it is impossible to see because it is on the inner layers, but here's how it looks from the top. You can still see some 17 mil vias with holes although even these are under the solder mask.

Here we go. That's what I suspected. Still it's not a viable option for me as my board are usually rather large (FPGAs need several power rails and it's not a good idea to have them off-board because that degrades converters' transient response), so it still is cheaper to order them at the likes of PCBWay (and I need a stencil as well). I did cheat in my Artix-7 board as well and made annual ring of only 0.125 mm instead of 0.15 mm as they require, but boards came out OK (at least ones I've checked).
And for DDR3 memory I will need 6 layers by the looks of it - at least so far I was unable to successfully route it on 4 layers.

[NorthGuy]

I did cheat in my Artix-7 board as well and made annual ring of only 0.125 mm instead of 0.15 mm as they require, but boards came out OK (at least ones I've checked).

This is actually 2 mil you have cheated. I only cheated 1 mil

And for DDR3 memory I will need 6 layers by the looks of it - at least so far I was unable to successfully route it on 4 layers.

Micron has a technical note: "TN-41-08: Design Guide for Two DDR3-1066 UDIMM Systems"

It is about DIMMs (and 2 of them), so probably not exactly what you're doing, but they suggest 4-layer board, they discuss routing, impedance etc. May be of interest to you.

I had an idea of 256-pin Artix-7 with SO-DIMM. I wanted to place Artix-7 on one side and SO-DIMM on the other side. Half of the DQ lines from the same group would go on the top layer (where FPGA is) then they would have vias next to the far end of the SO-DIMM socket. The other half would go straight to the bottom from the dogbone, then would travel the bottom layer and would connect to the near side of the SO-DIMM connector. This way it is easier to match lengths and it is only one via for each line.

I started this it, and I even routed three groups, but then I abandoned this idea and decided that I would better go with 484-pin Artix-7 and 6-layer board. I would even go with 676-pin model, but they're expensive and have horrible pinouts.

What was the problem with your routing?

[mrpackethead]

Im doing a BGA design right now ( 4 layer, 389 pin )..  .8mm pitch.  Forutnatly the designers of the chip have done a good job of laying it out..  I've gone for via in pad,  it will be .2mm vias.. This lets me use 0402 caps for decoupling rather than 0201, which pushes my assembly process just a bit too far.

[asmi]

This is actually 2 mil you have cheated. I only cheated 1 mil

But to be absolutely honest I've done this before multiple times with both PCBWay and allpcb, and in all cases boards came out good, and they never said anything about it. So I was relatively certain of favorable outcome. I just thought that I'm the only one who plays chicken with PCB houses

Micron has a technical note: "TN-41-08: Design Guide for Two DDR3-1066 UDIMM Systems"

It is about DIMMs (and 2 of them), so probably not exactly what you're doing, but they suggest 4-layer board, they discuss routing, impedance etc. May be of interest to you.

Thanks.

I had an idea of 256-pin Artix-7 with SO-DIMM. I wanted to place Artix-7 on one side and SO-DIMM on the other side. Half of the DQ lines from the same group would go on the top layer (where FPGA is) then they would have vias next to the far end of the SO-DIMM socket. The other half would go straight to the bottom from the dogbone, then would travel the bottom layer and would connect to the near side of the SO-DIMM connector. This way it is easier to match lengths and it is only one via for each line.

That won't work, because DDR3 controller requires all pins to be in the same IO column. And you'd better not use right column (IO banks 14 and 15) because they contain configuration pins which are required to be on certain voltage domain during bootup stage (like QSPI flash pins for example that can only be 1.8 or 3.3 V depending on what IC do you use). So while it's theoretically possible though the use of voltage translators, MIG datasheet and wizard strongly advise against it.
But because left column has one of two IO banks only partially bonded out (specifically only one DQ group of the bank 34 is fully bonded out, and other one partially), you can only use a single x8 DDR3 chip with that package as MIG wizard doesn't allow to pick anything from bank 34. So unless I'm missing something (or will be willing to play games with voltage translation), you can't have anything other than x8 chip with that package.

I started this it, and I even routed three groups, but then I abandoned this idea and decided that I would better go with 484-pin Artix-7 and 6-layer board. I would even go with 676-pin model, but they're expensive and have horrible pinouts.

I'm thinking about making a devboard out of 484 package on a 6-layer using 0.1/0.1/0.2 mm process as this will allow me to fit two traces between vias, which in turn should allow to fully route out all pins on the package without major hassle. The reason is I want to make a Gameboy-kind of device and FPGA will need to drive LCD via 24-bit parallel port (+ pins for the touchscreen), and that is in addition to the memory (which by itself will consume two IO banks because of IO voltage requirement), and since two banks will be involved, I might as well go all the way and route 4 byte groups for 32bit-wide bus - this will allow me to practice fly-by routing for address/control lines too

What was the problem with your routing?

A couple of issues - one was that I couldn't come up with the way to route out all lines of ADDR/CTRL group on a single layer while maintaining length matching. Another one was that traces took all the space on the bottom layer, so I had no space to put decoupling caps for that bank, and from what I understand that is a big no-no especially when you have so many fast switching pins in the bank.
Placing ADDR/CTRL bus traces on different routing layers would not work because of the stackup I've chosen (signal-power-signal-ground, which is, while not optimal, gave me more routing space in the critical breakout region as decoupling caps did not interfere with signal traces). The problem here is that propagation delay for inner and outer layers is different because of different effective dielectric constant of the air vs prepreg.
The bottom line is I wasn't able to route it while complying with all DDR3 memory interface requirements and recommendations, and while it might just work, spending $200 or boards + ~$100 on components to find out seemed like not the best idea.
With that said, I found that AM3354 SoC from TI in "Via Channel" package was specifically designed to be routed out on 4 layer boards, and it has DDR3 interface among others, and this sounds very convincing for me to just take the risk and give it a try. So I might as well do just that - but a little later, as my purchase of Orcad PCB Editor Pro will wipe out all my hobby money for the next several months, and by spending more I run the risk of being kicked away from home by my wife But at least with that CAD package I can actually run IBIS simulations and be reasonably sure it will work if the sim will say so. So stay tuned!

[NorthGuy]

That won't work, because DDR3 controller requires all pins to be in the same IO column. And you'd better not use right column (IO banks 14 and 15) because they contain configuration pins which are required to be on certain voltage domain during bootup stage (like QSPI flash pins for example that can only be 1.8 or 3.3 V depending on what IC do you use).

I was going to run all banks at 1.5V. According to my reading of the config docs this should be Ok. Then I would use level shifters for the flash, PIC, and SPD. I also wanted to add Ethernet PHY running at 1.5V. SO-DIMM would require 8 byte groups, so I would completely use banks 14, 15, and 35, with bank 34 left for test pins. This was meant to be a test board.

I was going to go by Micron recommendations (signal-power-ground-signal). This would give me two signal layers with the same impedance characteristics. The capacitors are certainly very important at this speed, but I was going to insert them inter-layer outside of FPGA - not much choice here. Xilinx says within an inch of FPGA, so it might have worked Ok. You may try that too. And if you go (signal-power-ground-signal) you can split the control lines between layers. Also Address/Control lines are less important than DQ/DSQ, so you can give them more slack.

Now I think of the 484-layout. They have banks 14,15 and 16 together which I want to run on 1.5V and connect all the stuff to them. Then I can test the core and once this is done, I can grow useful board from the other side - banks 34, and 35 (and 13 if I get a bigger chip). I'll go with (slow signal-power-signal-power-signal-ground) layers. This also will give me two signal layers with the same impedance characteristics, and since they're striplines, I will be able to get away with much more narrow traces. So, I think SO-DIMM is well within the reach.

I already have a component box with enough stuff to build 5-6 revisions. I don't have much time to design the board though

[asmi]

I was going to run all banks at 1.5V. According to my reading of the config docs this should be Ok. Then I would use level shifters for the flash, PIC, and SPD. I also wanted to add Ethernet PHY running at 1.5V. SO-DIMM would require 8 byte groups, so I would completely use banks 14, 15, and 35, with bank 34 left for test pins. This was meant to be a test board.

Now I'm looking at schematic of my board, and I noticed that I don't use any of bank 15 pins for config (because I use QSPI flash), as for bank 14 the only "special" pin (aside from QSPI ones obviously) is PUDC, which controls whether IO pins' pullups are going to be on or off during configuration. I also have main clock input here, but this is irrelevant as it can be pretty much any MRCC pin. So what you're saying might actually work. Gotta verify this in Vivado though as I've already made enough stupid mistakes by choosing wrong pin for the clock on the first spin of the board Actually that first spin was such huge disaster as I couldn't believe just how many mistakes I've made (and still do - even in rev 2 I use SRCC pin for clock instead of MRCC ) I guess I was too scared by MIG's warnings
BTW - what would you need PIC for? Microblaze seems plenty powerful, and you can stuff several of them inside FPGA if one is not enough (and you've got some LUTs/FFs to spare).

I was going to go by Micron recommendations (signal-power-ground-signal). This would give me two signal layers with the same impedance characteristics. The capacitors are certainly very important at this speed, but I was going to insert them inter-layer outside of FPGA - not much choice here. Xilinx says within an inch of FPGA, so it might have worked Ok. You may try that too. And if you go (signal-power-ground-signal) you can split the control lines between layers. Also Address/Control lines are less important than DQ/DSQ, so you can give them more slack.

Or you can expose power/gnd vias on the bottom of the board under the BGA and manually solder these caps (BGA pitch is 1.0 mm and so is the size of 0402). The reflow will likely fail in this case as solder will be wicked into vias, but manual soldering should do as a sort of poor-man via-in-a-pad. Hmm, interesting

Now I think of the 484-layout. They have banks 14,15 and 16 together which I want to run on 1.5V and connect all the stuff to them. Then I can test the core and once this is done, I can grow useful board from the other side - banks 34, and 35 (and 13 if I get a bigger chip). I'll go with (slow signal-power-signal-power-signal-ground) layers. This also will give me two signal layers with the same impedance characteristics, and since they're striplines, I will be able to get away with much more narrow traces. So, I think SO-DIMM is well within the reach.

BTW as example - here are PCBWay's standard stackups for 6-layer boards (core thickness shown there includes copper layers on both sides of it, so you gotta sub 0.07 mm to get dielectric thickness, 7628 is 0.185 mm, 2116 is 0.105):

1.6 mm version kinda sucks for high-speed design, but 1.2 mm seems alright (low-speed/gnd/hi-speed/hi-speed/power/low-speed) - Orcad calculated 0.1897 mm trace for 50 Ohm single-ended impedance, and 0.1512 mm tracks with 0.3 mm separation for 100 Ohm differential impedance (for edge-coupled traces,). Not too bad at all I would say. The only real concern is that thin prepreg between hi-speed layers - will have to make sure that crosstalk is in check.

I already have a component box with enough stuff to build 5-6 revisions. I don't have much time to design the board though

I stopped buying components "just in case" some time ago as I already have two boxes of parts which I can't remember what did I buy them for So now aside from passives and things like chip LEDs, I tend to buy parts when I actually need them. With Digikey/Mouser's next business day delivery it's not too bad.

[NorthGuy]

BTW - what would you need PIC for?

Lots of different small tasks - power sequencing, reset, communications with PC (perhaps SPD too), storing some settings etc.

Or you can expose power/gnd vias on the bottom of the board under the BGA and manually solder these caps (BGA pitch is 1.0 mm and so is the size of 0402). The reflow will likely fail in this case as solder will be wicked into vias, but manual soldering should do as a sort of poor-man via-in-a-pad. Hmm, interesting

I am not that good at soldering. I'd better put the caps on top and reflow everything. Unless absolutely necessary.

BTW as example - here are PCBWay's standard stackups for 6-layer boards (core thickness shown there includes copper layers on both sides of it, so you gotta sub 0.07 mm to get dielectric thickness, 7628 is 0.185 mm, 2116 is 0.105):

Thanks. This is a good stackup. I like 1.6mm better because it's uniform. In the quotation form, they offer custom stackup and it is just $20 extra or so. Don't know if that's true,

1.6 mm version kinda sucks for high-speed design, but 1.2 mm seems alright (low-speed/gnd/hi-speed/hi-speed/power/low-speed) - Orcad calculated 0.1897 mm trace for 50 Ohm single-ended impedance.

Strange. The online calculator for striplines ( http://www.mantaro.com/resources/impedance-calculator.htm )  shows smaller values. For 50 Ohm, it calculates 8 mil for the 1.6mm board. For the 1.2mm stackup, it calculates 7 mil if the signal layer sits against the outer pre-preg and 4 mil if the signal layer sits against the central (thinner) pre-preg.

I tend to buy parts when I actually need them. With Digikey/Mouser's next business day delivery it's not too bad.

Sometimes, you design and print a board and then you see that the part which you used is no longer in stock. I came across such situation few times. Now I order all the parts before I print boards.

[asmi]

Lots of different small tasks - power sequencing, reset, communications with PC (perhaps SPD too), storing some settings etc.

I see. I use TPS65400 to power the FPGA, it's got built-in support for sequencing (even though it's not that important with 7 series FPGAs).

I am not that good at soldering. I'd better put the caps on top and reflow everything. Unless absolutely necessary.

I usually reflow both sides as well. But in that case I'd have to use via as a pad, and reflow would likely fail in this situation.

Thanks. This is a good stackup. I like 1.6mm better because it's uniform. In the quotation form, they offer custom stackup and it is just $20 extra or so. Don't know if that's true,

I don't know either. Their calculator is kinda wonky.

Strange. The online calculator for striplines ( http://www.mantaro.com/resources/impedance-calculator.htm )  shows smaller values. For 50 Ohm, it calculates 8 mil for the 1.6mm board. For the 1.2mm stackup, it calculates 7 mil if the signal layer sits against the outer pre-preg and 4 mil if the signal layer sits against the central (thinner) pre-preg.

This is what I've got (numbers are slightly different since last time I forgot to set a proper dielectric constant - 4.29 as per PCBWay's support)

Sometimes, you design and print a board and then you see that the part which you used is no longer in stock. I came across such situation few times. Now I order all the parts before I print boards.

I try using only parts that are in stock in multiple sources. But whenever I do order parts, I usually order in quantity of 10 as usually that's where next price tier is so I will have some surplus in case I mess up assembly (unless they are super expensive parts like FPGAs - these things I usually buy however many I need + 1 just in case). For passives I usually "pad" my orders to get free shipping with full reels of 0402 components as they are very cheap anyway, and I slowly build up an inventory of them.

[Cerebus]

I don't want to be a killjoy, but you're kind of hijacking the thread guys. (I know, pot calling kettle black; I've been rather guilty of this myself.)

[NorthGuy]

I don't want to be a killjoy, but you're kind of hijacking the thread guys. (I know, pot calling kettle black; I've been rather guilty of this myself.)

Guilty

[Corporate666]

Price is NO indicator.. The cheaper fab might actually be better.   The only way you can find out is to try them out...     And its the 'total' quality that you've got to take into account. thats ontime delviery, easy to use.. If i have to spend hours sorting out drama because its too hard,  then it coudl be free, but it woudl still be expensive if that makes sense.      I've found that for all my 'basic' PCBs ( thats stuff that is 4 layer, .15/.15 and .3mm min vias ) that AllPCB have done a really good job.   Mostly on time, they ahve owned their mistakes and they are easy to communicate. It took a bit of time to work otu what they were about though, and all their changes dont' make it easy.

Oh, I absolutely agree.  My point was that if a PCB fab is more expensive because they are spending more man-hours making the boards to a high standard, or because they have better equipment or tighter tolerances causing more scrap, then to many customers, that is a selling point and they will gladly pay more. 

Being more expensive is fine, provided I am getting something more for my money.  I dislike when a company is more expensive but tries to hide it (like by having add-on fees that aren't shown when you're browsing the site and price-checking). 

I posted an experience with PCBWin and I was exceptionally happy with them.  I ordered 1000pcs of a small board.  They were a bit more expensive, but not by much... and those 1000 PCB's represent $50,000 worth of revenue to my company, so I couldn't care in the slightest if the PCB order was $220 vs $190 somewhere else.  Having the boards done right with good communication and options I can choose from (as posted above) is worth that $30 and more.  Shipping out even 2 or 3 bad PCB's or having to rework PCB's that are shoddy from the get-go will eat up 100 times the cost savings on the initial order.

[mrpackethead]

I posted an experience with PCBWin and I was exceptionally happy with them.  I ordered 1000pcs of a small board.  They were a bit more expensive, but not by much... and those 1000 PCB's represent $50,000 worth of revenue to my company, so I couldn't care in the slightest if the PCB order was $220 vs $190 somewhere else.  Having the boards done right with good communication and options I can choose from (as posted above) is worth that $30 and more.  Shipping out even 2 or 3 bad PCB's or having to rework PCB's that are shoddy from the get-go will eat up 100 times the cost savings on the initial order.

But it seems that just because you pay $30, $80 or -$20 in comparison to another board house it is no indicator of the quality.   Its a bizzare and strange market.